1. Field of the Invention
This invention relates to industrial ball valves installed in pipe lines in manufacturing plants and commercial buildings.
2. Description of Prior Developments
Recent federal safety legislation requires a zero energy lockout condition when industrial machinery is being torn down or repaired. In the case of machinery that uses pressurized fluids the requirement will have to be satisfied by having valves that have a positive means for locking the valves in their closed positions while the associated machinery is under repair.
Many pressurized fluid systems use manually-operable ball valves for controlling the fluid flow. A typical ball valve has an operating handle extending right angularly from a rotary stem that projects from the ball valve housing; the stem serves as a connector between the ball element within the valve housing and the external handle. When the ball valve element is in the flow-open position the handle extends parallel to the flow passage in a plane coincident with the associated pipe line. To close the valve the handle is turned one quarter revolution so that the handle extends in a plane extending generally crosswise of the pipe line.
It would be possible to build lockout devices into ball valves to ensure that they remain in their closed positions while maintenance operations are being performed on the associated machinery, i.e. machinery that is normally supplied with pressurized fluids controlled by the ball valves. However, this would require replacement of existing ball valves, with the attendant expense related to the cost of the new valves, the labor cost of removing the old valves, and the labor cost of installing new valves. There would also be some expense due to the machinery being inoperative while the old valves were being removed and the new valves were being installed.